Copyist, having removed margins, limits data form (8)
I believe the answer is:
imitator
'copyist' is the definition.
(thesaurus)
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for imitator that I've seen before include "Someone copying the behaviour of another" , "Copycat" , "follower" , "A trio, Tim, is a mimic" , "parrot" .)